The thorns of lime trees can cause skin irritations such as rashes and blisters and a condition called phytophotodermatitis. Here is an article that describes the condition
The thorn is not "toxic" in terms of causing a life-threatening condition but is phototoxic in that scraping the skin causes a reaction, similar to getting poison ivy http://www.sciencedaily.com/releases/2007/08/070815153545.htm . If you are looking for relief for the irritation or pain, I recommend you visit a nearby 24 hour walk in clinic and ask the doctor how severe the reaction is and if there is a topical ointment you can use.
I hope this helped and let me know if you have any questions about the information I provided.